On FIRST’s website, there appears to be two different times for stop build. In the event, it says 11:59PM local time on 2/23/16. However, the date for the event says 12:00AM on 2/23/16. I can’t seem to figure out which date is actually stop build. Has anyone else figured this out?
From what I’ve heard, it’s 11:59 Tomorrow night, local time.
Section 5.1 of the admin manual is the ultimate authority:
All teams must cease work on their robot on or before Stop Build Day. Any team that fails to comply may jeopardize their participation in the rest of the FIRST Robotics Competition season. Note that “Stop Build Day” is a specific date. You may work on your robot until midnight local time on Stop Build Day.
STOP BUILD DAY IS TUESDAY, FEBRUARY 23, 2016
I can see where things get confusing.
If you scroll down to “Stop Build Day” in the calendar, it says:
02/23/2016 - 12:00am.
Then when you click on the link it says:
Date: February 23, 2016
Time: 11:59 PM (local time)
These are almost a day apart. Based on precedent, it would seem that Stop Build will happen on the night of the 23rd (tomorrow night) rather than tonight.
This comes up almost every year. It looks like by saying 11:59 pm they’ve realized that midnight starts the day, not ends it. But they didn’t find all references to midnight to clarify it.
Which is why we always stop at Tuesday night at 11:53 pm 
Stop Build Day is the entire day. That’s why the calendar entry begins at 12 am. Lots of single-day events (e.g. off-season competitions) are listed that way too.
The deadline for bagging the robot is the end of the day, given as 11:59 pm.
Um shouldn’t that be 11:59 PM?
12:59 PM is the middle of the afternoon.